Wafer Bonding

The profound know how of Micronit GmbH allows the fabrication of systems with up to 21 glass layers as well as closed chambers which can be used for reference pressure measurements in a chip. For MEMS applications free suspended membranes of oxide or nitride are required, which are build using bonding and back etching.

There are different wafer bonding techniques such as

Fusion bonding of silicon

Fusion resp. direct bonding of glass

Eutectic bonding

Anodic bonding

Thermo-compression bonding

Adhesive bonding

Fusion or Direct Bonding

Fusion or direct bonding is a technique whereby two or more wafers of the same material are joined together. Fusion bonding is conducted at high temperatures, which makes the bond as strong as the mechanical strength of the base material. However, direct bonding at lower temperature is also feasible.

Applications

Applications

Anodic Bonding

Anodic bonding is a bonding technique whereby two or more wafers of different materials (silicon with glass) are bound together. The bonding is done at low temperatures.

The process of anodic bonding is usually done at 400°C that is at lower temperatures as with direct bonding. For the European project BIOINTENSE Micronit developed a special low temperature bonding process at less than 180°C. The low temperature maintains the biological/chemical characteristic of the infused sensors and reduces the tension in glass and silicon layers.

Technical Details

Technical Details

Silicon to glass

SOI or SDOI to glass

Triple-stack-bonding (Glass-Si-Glass)

Aligned bonding

Vacuum bonding

Pressure definde bonding

Integration of electrodes

Integration of bio sensores, f.e. oxygen sensors

Hermetic connection

Applications

Applications

MEMS structures

MEMS sensors

Cover lid for microfluidic channels

Packaging

Channel port connections

BioMEMS devices

Lab-on-a-chip (LOC) or point-of-care (PoC)

MOMS

Eutectic Bonding

Using eutectic bonding means forging a material bound connection through application of pressure and temperature treatment between two silicon or glass wafers. An established eutectic alloy is gold-silicon.

Technical Details

Technical Details

Pressure up to 90 kN

Structures gold layser (thin film technique), not for adhesive

Combinations of other metals with silicon feasible, not for adhesive

Aligned bonding

Applications

Applications

MEMS packaging

3D Integration

Microfluidics / Lab-on-a-chip

Through-connection (via) f.e for BioMEMS

Adhesive Bonding

During adhesive bonding of PCB resp. SU-8 bonding polymers are applied to structures wafers and then structured with own layout. The bonding is done with a second wafer, which might be structured as well. Both wafers must not be necessarily of the same material.